US3810232A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic memory read system for digital recordings
Assignee: Singer Co
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Filing: 1972-10-18
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Granted: 1974-05-07
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Expires: 1992-10-18
Abstract
Abstract A magnetic memory read system for digital recordings is provided which utilizes peak detection principles to reconstruct digital data recorded on a magnetic memory, such as a tape, drum or disc. The read system incorporates magnetic data reconstruction circuitry which employs both zero crossing-detecting means and threshold detection means in two channels which are ultimately combined to accurately detect the output of a magnetic read head at very high and very low peak densities. An enabling signal is developed in the second channel which permits precisely phased signals of the first channel to pass to the output for reconstruction into a corresponding data signal, but which disables the output with respect to spurious signals detected in the first channel, for example, to ''''shoulders'''' in the output signal of the read head. These ''''shoulders'''' appear as the packing density of the digital recordings on the magnetic medium falls below a particular threshold.
Inventors
- 👤 S Aghazadeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:59
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
168 words
A demodulation system for reconstructing digital data recorded by phase modulation on a magnetic medium, said system including: a transducer for sensing the digital recordings on the magnetic medium and for transforming the recordings into a corresponding phase modulated signal; differentiating circuitry coupled to said transducer for producing a differentiated output signal corresponding to said phase modulated signal; first circuitry including zero-crossing detecting means coupled to said differentiating circuitry for producing output pulses representative of the crossing by said differentiated signal of a particular reference axis; second circuitry including threshold detecting means coupled to said differentiating circuitry for producing an enabling signal representative of the crossing by the peaks of said differentiated signal of predetermined threshold axis; and gate means coupled to the outputs of said first and second circuitry and responsive to said output pulses and to said enabling signal for producing an output only when an output pulse from said first circuitry coincides with a particular amplitude state of the enabling signal from said second circuitry.
Claim 2
Dependent Claim
168 words
A demodulation system for reconstructing digital data recorded by phase modulation on a magnetic medium, said system including: a transducer for sensing the digital recordings on the magnetic medium and for transforming the recordings into a corresponding phase modulated signal; differentiating circuitry coupled to said transducer for producing a differentiated output signal corresponding to said phase modulated signal; first circuitry including zero-crossing detecting means coupled to said differentiating circuitry for producing output pulses representative of the crossing by said differentiated signal of a particular reference axis; second circuitry including threshold detecting means coupled to said differentiating circuitry for producing an enabling signal representative of the crossing by the peaks of said differentiated signal of predetermined threshold axis; and gate means coupled to the outputs of said first and second circuitry and responsive to said output pulses and to said enabling signal for producing an output only when an output pulse from said first circuitry coincides with a particular amplitude state of the enabling signal from said second circuitry.
Claim 3
Dependent Claim
28 words
The modulation system defined in claim 1, in which said first circuitry includes delay means for establishing a predetermined timing between said output pulses and said enabling signal.
Claim 4
Dependent Claim
53 words
The demodulation system defined in claim 2, in which said second circuitry includes multivibrator means for producing said enabling signal with a rectangular wave form having first and second amplitude values to cause said gate means to be enabled only when said enabling signal has a particular one of said two amplitude values.
Claim 5
Dependent Claim
45 words
The demodulation system defined in claim 1, in which said output pulses produced by said first circuitry include spurious pulses, and in which said second circuitry includes a low pass resistance/capacitance filter means to prevent corresponding spurious signals from being introduced into said enabling signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |